Which expression is a polynomial in x but not quadratic in x?
Answer and explanation
Correct answer: 6x³ − 2x + 9
A polynomial in x has only non-negative integral powers of x, and its degree is the greatest power with a non-zero coefficient. A quadratic polynomial must have degree exactly 2. Option B, 6x³ − 2x + 9, contains only powers 3, 1, and 0, so it is a valid polynomial; its degree is 3, making it cubic rather than quadratic. Option A is quadratic because its degree is 2. Option C contains x⁻¹ because 5/x = 5x⁻¹, so it is not a polynomial. Option D contains x^(1/2), which is also not an allowed integral power. Therefore, B is the only suitable expression.
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What is the correct answer to this question?
6x³ − 2x + 9
Why is this the correct answer?
A polynomial in x has only non-negative integral powers of x, and its degree is the greatest power with a non-zero coefficient. A quadratic polynomial must have degree exactly 2. Option B, 6x³ − 2x + 9, contains only powers 3, 1, and 0, so it is a valid polynomial; its degree is 3, making it cubic rather than quadratic. Option A is quadratic because its degree is 2. Option C contains x⁻¹ because 5/x = 5x⁻¹, so it is not a polynomial. Option D contains x^(1/2), which is also not an allowed integral power. Therefore, B is the only suitable expression.
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Polynomials. Topic: Polynomials in one variable.
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